package demo1;

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        int n = in.nextInt();
        int[] arr = new int[n];
        for(int i = 0; i < n; i++) {
            arr[i] = in.nextInt();
        }
        for(int i = n-1; i >= 0; i--) {
            int max = 0;
            int d = 0;
            for(int j = 0; j < i; j++) {
                d = arr[i]-arr[j];
                if((d > max)) {
                    max = d;
                }
            }
            arr[i] = max;
        }
        int a = 0;
        for(int i = 0; i < n; i++) {
            if(arr[i] > a) {
                a = arr[i];
            }
        }
        System.out.println(a);
        
    }
}